The present invention relates to a method for fabricating a semiconductor device and a substrate processing apparatus; and, more particularly, to a semiconductor device fabricating method including a depressurization process and a substrate processing apparatus performing same.
Referring to FIG. 1, there is illustrated a conventional substrate processing apparatus having a vertical type reaction furnace.
In the substrate processing apparatus, a reaction tube 1 is mounted on a manifold 2, which also supports an inner tube 3 that is vertically aligned with the reaction tube 1. The reaction tube 1 is enclosed by a tubular heater 4, wherein the reaction tube 1 and the tubular heater 4 constitute a reaction furnace.
The interior of the reaction tube 1 constitutes a hermetically sealed reaction chamber 5, which communicates with an airtight waiting room 6 defined within a load-lock chamber 7 connected to a lower portion of the manifold 2. Further, installed in the load-lock chamber 7 is a boat elevator 30 for loading and unloading a substrate holder 8 (hereinafter, referred to as a boat 8) into and from the reaction chamber 5, wherein an elevator cap 9 is used to hermetically close the reaction chamber 5 after the boat 8 is completely loaded thereinto.
The load-lock chamber 7 has a gate valve therein (not shown), and a wafer transferring device (not shown) is installed outside the load lock chamber 7. The wafer transferring device performs loading and unloading of substrates 10 such as Si wafers (hereinafter, referred to as wafers 10) via the gate valve, while the boat 8 is stationed in the load-lock chamber 7.
Connected to the manifold 2 are a first gas supply line 11 and a first exhaust line 13, wherein the first gas supply line 11 introduces gas to the bottom portion of the inner tube 3. In a similar fashion, a second gas supply line 12 and a second exhaust line 14 are connected to the load-lock chamber 7. The exhaust lines 13, 14 are connected to an exhaust system (not shown) via air valves 15, 16, respectively.
The boat 8 holding a predetermined number of wafers 10 is loaded into the reaction chamber 5, which is then vacuum-evacuated, and the boat 8 and the wafers 10 are heated by the heater 4 therein. A reaction gas then is supplied to the reaction chamber 5 through the first gas supply line 11, while the reaction chamber 5 being exhausted in order to maintain a predetermined depressurized state, so that film forming process can take place under a specified process condition. After a completion of the wafer process, the boat 8 is de-elevated and wafers 10 are unloaded therefrom.
Conventionally, the reaction chamber 5 and the waiting room 6 are both either kept in the atmospheric state or supplied with nitrogen gas thereto, while the boat 8 is being loaded into the reaction furnace.
However, when the reaction chambers 5 and the waiting room 6 are both kept in the atmospheric state, formation of natural oxide films on the wafers 10 occurs during the process of loading the boat 8 into the reaction chamber 5, which entails an adverse effect on the semiconductor device.
On the other hand, by supplying nitrogen gas into the reaction chamber 5 and the waiting room 6, the formation of the natural oxide film can be dramatically reduced compared to the aforementioned case. Since, however, oxygen can not be completely removed even in the nitrogen atmosphere, natural oxide film formation may not be completely prevented.
Therefore, another method has been introduced, in which the reaction chamber 5 and the waiting room 6 are vacuum-evacuated during the process of transferring the boat 8 between the reaction chamber 5 and the load-lock chamber 7. In this case, the formation of natural oxide films is further suppressed compared to the aforementioned two cases.
However, it has been found by the inventors of the present invention that while the vacuum-evacuated reaction chamber 5 and the waiting room 6 suppresses formation of natural oxide films, contaminant particles are formed on the wafers 10.
In particular, significant generation of such contaminant particles was observed during the time at which the boat 8 is loaded into the reaction chamber 5 and the temperature recovery period (recovering temperature loss, which occurs during loading of the boat 8) of the reaction chamber 5 and also, while the temperature of the wafers 10 was raised to a processing temperature.
It is therefore, an object of the present invention to provide a substrate processing apparatus and a method for fabricating semiconductor devices, which reduces a formation of natural oxide film and generation of contaminant particles, thus improving quality of semiconductor devices.
In accordance with one aspect of the present invention, there is provided a semiconductor device fabricating method, including the steps of: loading one or more substrates into a boat disposed in a waiting room positioned next to a reaction furnace; vacuum-evacuating the waiting room to a vacuum state at a base pressure; loading the boat into the reaction furnace at a first ambient pressure; and recovering a temperature of the reaction furnace at a second ambient pressure, wherein the first or the second ambient pressure is greater than the base pressure but less than the atmospheric pressure.
In accordance with another aspect of the invention, there is provided a semiconductor device fabricating method, including the steps of: vacuum-evacuating a reaction furnace to a vacuum state at a base pressure; loading a boat having one or more substrates into the reaction furnace; recovering a temperature of the reaction furnace at a recovery pressure; and processing said one or more substrates by supplying one or more processing gases into the reaction furnace, wherein the recovery pressure is greater than the base pressure but less than the atmospheric pressure.
In accordance with still another aspect of the invention, there is provided a semiconductor device fabricating method, including the steps of: vacuum-evacuating a reaction furnace to a vacuum state at a base pressure; increasing a temperature of one or more substrates supported by a boat in the reaction furnace at an ambient pressure; and processing said one or more substrates by supplying one or more processing gases into the reaction furnace, wherein the ambient pressure is greater than the base pressure but less than the atmospheric pressure.
In accordance with still another aspect of the invention, there is provided a semiconductor device fabricating method, including the steps of: loading a boat having one or more substrates into a reaction furnace; vacuum-evacuating the reaction furnace to a vacuum state at base pressure; processing said one or more substrates by supplying one or more first processing gases into the reaction furnace at a first processing temperature and at a first ambient pressure; processing said one or more substrates by supplying one or more second processing gases into the reaction furnace at a second temperature and at a second ambient pressure; and performing a temperature change from the first processing temperature to the second processing temperature at an intermediate ambient pressure; and wherein the intermediate ambient pressure is greater than the base pressure but less than the atmospheric pressure.
In accordance with still another aspect of the invention, there is provided a substrate processing apparatus including: a reaction furnace for processing one or more substrates; a substrate holder for supporting said one or more substrates; a waiting room connected to the reaction furnace; a substrate holder transferring means for transmitting the substrate holder between the waiting room and the reaction furnace; and a pressure controlling means for maintaining the waiting room at a base pressure after loading said one or more substrates into the substrate holder disposed in the waiting room; at a first ambient pressure when loading the substrate holder from waiting room to the reaction furnace; a second ambient pressure in the reaction furnace while a temperature of the reaction furnace is recovered after loading the substrate holder thereinto; then a third ambient pressure in the reaction furnace while increasing a temperature of said one or more substrates to a processing temperature, wherein the first, the second or the third ambient pressure are higher than the base pressure but less than the atmospheric pressure.
In accordance with still another aspect of the invention, there is provided a substrate processing apparatus including: a reaction furnace for processing one or more substrates; a substrate holder for supporting said one or more substrates; a pressure controlling means for vacuum-evacuating the reaction furnace to a vacuum state at a base pressure; maintaining the reaction furnace at a first ambient pressure while a temperature of the reaction furnace is recovered after loading the substrate holder thereinto; and maintaining the reaction furnace at a second ambient pressure while increasing a temperature of said one or more substrates to a processing temperature, wherein the first or the second ambient pressure is higher than the base pressure but less than the atmospheric pressure.